The present invention concerns a so-called “polishing” water filter for micro-filtration of extremely fine mineral particles, biological microorganisms and the like. The invention further relates to a method of making such a polishing water filter and to methods of using this water filter.
Many waste water treatment plants are now being built utilizing micro-filtration technology. This technology is designed to remove microorganisms such as giardia, which are about 3 microns wide and about 10 microns-long. Over time, fibers within the micro-filtration filter can break off, leaving openings up to 400 microns wide so that the giardia pass through. No known means are presently available to block these microorganisms, short of adding a further micro-filtration unit.
Water desalinization plants typically operate using reverse osmosis (RO) membranes that are very expensive and fragile. Such membranes are also susceptible to clogging by undissolved particles and by microorganism growth on the membrane. For example, a Total Organic Carbon (TOC) load of only one milligram per liter is enough food for microorganism growth to occur thereby causing a condition known as biofouling on the membrane. Any pre RO treatment process that can lower the TOC content of the RO feed water will greatly enhance the RO membrane performance. Less frequent chemical cleanings would be required thereby prolonging the life of the membranes. Also, The main function of an RO membrane is to remove dissolved salts and other molecular components from the water. The best possible pretreatment is a major goal in the RO process.